Weather and Plants

It seems as if summer will never arrive this year. Just as we anticipate a rise in the temperatures, a cold, wet front moves in. Record rainfalls, heat waves in January, sleet and snow in spring, and April showers in May are enough to throw our plants into a spin.

The result of this crazy weather pattern is little growth found in our plants that require warmer soil temperatures. For example, summer vegetables need soil temperatures in the stable 60s for growth. Tomatoes planted in the ground may not show much sign of development unless they are placed in an area that gets reflected heat. In order to provide temperature stability right now, try placing flat rocks around the plants. The rocks collect the solar heat during the day and release that heat into the soil at night. Another trick is to plant your vegetables in black plastic nursery cans. Again, the black plastic captures the heat, which transfers to the soil. Once the weather stabilizes, you can transplant the veggies into the ground.

The unstable weather conditions can wreak havoc with the health of our plants. Poor weather and air circulation around plants could potentially create the perfect breeding ground for fungus. Fungus can show up on the leaves of your plants in the form of black spot or rust. Roses are typically affected by this malady. Powdery mildew will also attack most ornamental plants, such as lilacs and euonymus.

If you see signs of powdery mildew, mix into one gallon of water:

3 tablespoons baking soda;

3 tablespoons horticultural oil, or vegetable, olive or corn oil; and

a few drops of dish soap.

Spray on the affected plants and repeat if the mildew comes back.

I also have been told you can use milk as a remedy. I haven’t tried that one, but let me know if it worked for you.

Now would be the time to install a rain shutoff device, if you don’t have one. The unstable weather conditions may have you wondering if you should or shouldn’t irrigate. Even with the water district’s sophisticated equipment, it can be difficult for us to make that call due to the many microclimates in Marin. A rain shutoff device will take the guesswork out of the equation. You won’t be wasting water if the ground it still wet, or parching your plants if it is too dry.